Using the app's current microphone button, which is available to the right of the search bar, users can make nearly any type of Alexa request. This request can consist of things you might ask of an Amazon Echo, such as playing music, turning on smart lights, checking the weather, and so on.
Both first-party and third-party skills will work from within the Amazon app. The one limitation so far, noted by Khari Johnson of VentureBeat, is that the Door Lock API is not currently available, so smart locks can't be controlled through the app. Johnson also shares that while Alexa will be available to some users in the Amazon app today, it will be rolling out to all users over the next week.
Today's announcement hopefully means that existing Amazon Echo users will have a solid first-party experience on iOS, something that surprisingly has not been provided by the company's current Amazon Alexa app. It also opens up Alexa to any Amazon customer who doesn't currently own an Echo.